Date: Thu, 19 Jul 2007 09:43:45 +0200 From: Momchil Ivanov <idiotbg@gmail.com> To: "[LoN]Kamikaze" <LoN_Kamikaze@gmx.de> Cc: josh@tcbug.org, freebsd-stable@freebsd.org, Norberto Meijome <freebsd@meijome.net>, olli@lurza.secnetix.de Subject: Re: removing external usb hdd without unmounting causes reboot? Message-ID: <200707190943.55428.idiotbg@gmail.com> In-Reply-To: <469F101C.5060906@gmx.de> References: <200707181703.07480.idiotbg@gmail.com> <20070719130252.6880b967@localhost> <469F101C.5060906@gmx.de>
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--nextPart2876896.OHRNQ5nC26 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Content-Disposition: inline On Thursday 19 July 2007 09:17:48 [LoN]Kamikaze wrote: > Norberto Meijome wrote: > > On Wed, 18 Jul 2007 17:41:04 +0200 (CEST) > > > > Oliver Fromme <olli@lurza.secnetix.de> wrote: > >> another work-around > >> is to use the auto mounter daemon (amd(8)). It umounts > >> file systems automatically that are not in use. > >> Another nice feature of amd(8) is that you don't have > >> to mount the file system either -- Simply plug the USB > >> stick in, then access it, and amd(8) will automatically > >> mount it for you. > > > > Now, something I dont understand - amd runs > > at user level, and it mounts filesystems, and nothing dies when the > > filesystems go away (other than the obvious cases for the applications > > trying to write to the FS in question). Doesn't amd , at some point , > > have to tell the kernel 'please mount this filesystem' here or there? > > Isn't the kernel STILL involved in all this? and why doesnt the kernel > > panic when the FS goes away? > > The trick is that amd unmounts the device after a couple of seconds, so > when someone accidentally removes a usb drive, it doesn't really matter. > Amd will simply fail to mount it on the next access. If you remove the > device during or shortly after accessing it, it still will panic the > system. What is then the reason for the kernel not being able to unmount a filesyst= em=20 whose provider is no longer present? What in the process of unmounting deni= es=20 unmounting a filesystem whose provider is no longer available? Why can the= =20 kernel not just inform all programs that files have to be closed and are=20 unaccessible any more, then consider the fs as unmounted and remove any bit= s=20 of it left in the VM. Why can kernel not just ignore interruped/pending=20 writes to that fs, drop the data, return an error to the program that=20 initiated the write and just go on. =2D-=20 PGP KeyID: 0x3118168B Keyserver: pgp.mit.edu Key fingerprint BB50 2983 0714 36DC D02E =C2=A0158A E03D 56DA 3118 168B =20 --nextPart2876896.OHRNQ5nC26 Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.7 (FreeBSD) iD8DBQBGnxYz4D1W2jEYFosRAvuTAKCLCyeWJLbtDM7Dnf3xjTcmeBbBowCePu1o o65XuPyPWShBfVUZUufODag= =4XkN -----END PGP SIGNATURE----- --nextPart2876896.OHRNQ5nC26--
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